ABSTRACT
The chi-square test presented in this chapter is concerned entirely with categorical variables; those producing nominal data, that is, frequencies by categories or levels. Very often the design of our research study entails that the authors gather data that are categorical in nature. The numbers in the cells of this kind of table are frequencies – they are just a count of the number of cases (cars in this case) observed in each cell of the table. Notice from the table that, of the new cars, far more stopped at amber than drove on, whereas for the older cars, the frequencies of stopping and not stopping were almost equal. Their statistical test will tell us whether this difference in stopping proportions between the two sets of drivers can be considered significant or not.
